Wood encased pencil, lead therefor, and method of making same



July 11, 1950 J. R. GRIECO woon ENCASED PENCIL, LEAD THEREFOR, AND METHOD OF MAKING SAME Filed Sept. 14, 1949 a w 2 Tn, 1R m 0 V n W m A d S Patented July 11, 1950 WOOD ENCASED PENCIL, LEAD THEREFOR, AND METHOD OF MAKING SAME Joseph Raymond Grieco, Brooklyn, N. Y., assignor to Eagle Pencil Company, a corporation of Delaware Application September 14, 1949, Serial No. 115,644

22 Claims.

The present invention relates to lead pencils more especially of the familiar type in which the lead of grease-impregnated calcined graphite and clay is glued into a sheath of wood or the like.

As conducive to a clear understanding of the invention, it is noted that where the grease impregnated lead is subjected to acid treatment in order to afford a non-greasy surface to be effectively wet by the water soluble glue for security of bond therewith, a pitted and therefore mechanically weakened lead frequently results, and where in addition to or instead of such acid treatment, the lead is coatedwith small crystals or other solid particles to which the-glue effectively attaches, this would not reliably preclude processed lead into the sheath of wood or the like by conventional procedure with assurance of a thoroughly adequate bond of the unweakened lead to the sheath, resulting in a strong writing point.

Another object is to provide a lead pencil of the above type by which the efficacy of bond of the sheath by. means of adhesive, such as water soluble glue, to grease impregnated lead is effected without modification in the character of grease commonly employed for impregnating the lead, without impairing the thoroughness of lead impregnation and without modification in the conventional wood or glue used for assembly of the lead pencil and without modification in the physical conformation of the lead or the sheath.

It is a feature of the invention securely to affix to the surface of the lead, prior to the impregnation thereof, .a substantially grease impervious coating for effective anchorage thereto of the water soluble glue that bonds the lead with its sheath, the effectiveness of which coating will not be impaired by the subsequent grease impregnation of'the lead through a portion or portions thereof that are uncoated.

According to another feature of the invention, the grease impervious glue anchorage is in the form of film composed of any of a wide variety of film forming adhesives compatible with the 2 v adhesive that bonds the lead into its sheath and such film is applied as a very thin coating that does not penetrate substantially into the lead and therefore does not entail hard spots due to dried glue, to impair the writing qualities of thelead.

While the film could be applied over most-or even all of the lateral area of the lead, leaving substantially only the ends of the lead exposed for admission of grease thereto, it is :desirable for ease of grease impregnation to leave substantial proportions of the lead surface area uncoated with film and to do this in manner that still assures a secure bond of the lead to the sheath. To this end the film may be applied to the'lead in a pattern at a plurality of spaced filmed areas to provide a plurality of points of anchorage around the periphery of the lead substantially throughout its length, said pattern involving illustratively discrete spots of film distributed over the surface of the lead or alternatively uncoated areas so distributed, each of which is defined by a border of film thereabout; one specific embodiment comprising stripes of film lengthwise of the lead, such as in a helical pattern, preferably in multiple, such as a triple or quadruple thread diagonally distributing the writing pressure across the grain of the wood and reducing the likelihood of splitting a straight grained Wooden sheath, the film coating at least such fraction of the total surface area of the lead as is adequate for secure glue anchorage of the lead within its sheath; and such anchorage is adequate even though the major area of the lead be left uncoated in order to assure. ready admission of grease thereinto during the impregnation cycle.

In the accompanying drawings in which are shown one or more of various possible embodiments of the several features of the invention,

Fig. 1 is a diagrammatic View showing illustrative equipment for the application of the glue anchorage areas upon the lead,

Fig. 2 is a fragmentary view on a larger scale showing the .lead coated with one pattern of film prior to impregnation,

, Fig. 3 is a transverse sectional view taken on line 33 of Fig. 2,

Fig. 4 is a cross sectional fragmentary view on a still larger scale showing the processed lead after impregnation thereof and after excess grease has been wiped therefrom,

Fig.5 is a fragmentary cross sectional view on an enlarged scale of the completed pencil structure, and

Figs. 6 and 7 are views similar to Fig. 2 and on a somewhat smaller scale showing other patterns of film coating for the lead.

Any suitable equipment may be employed for automatically applying the glue anchoring material upon the unimpregnated lead. Illustratively, there is shown in Fig. l, in diagrammatic form, equipment for this purpose which may comprise a tank It] that contains the glue-anchoring material H in liquid state and into which dips a pick-up roller l2 engaged by a doctor roller l3, urged by spring l4 into firm engagement therewith to wipe off from the roller l2 all excess material beyond an extremely thin layer. This very thin layer istransferred to a rubber roller l5 engaging the pick-up roller [2 and that rubber roller in turn engages a print-- ing roller 16 for coating upon the lead I l' as the latter moves downward between said printing roller I 6 and a backing roller l8. Roller i8 is carried on an arm 38 pivoted at 31 and urged as by spring I S'against adjustable stop 32. which maintains a space (usually in the order of T; inch) between'rollers It and i8, which are thus adjusted to accommodate the thickness of the intervening lead and to exert thereon suificient pressure to assure rolling the lead in its traverse between the rollers.

The leads H are laid in a hopper 2t and are fedby feed roller 2! within said hopper which roller is grooved longitudinally'as at 22' to accommodate and drop the leads one by one into. the cleft between the printing roller it and backing roller l8, so that in the friction drive of the printing rcller l6 from the pick-up roller i2 and the intervening rubber roller i5 glue-anchoring material is transferred and coated upon: the unimpregnated lead which thereupon drops into a receiving box 23 therebelow.

The printin roller It may be plain and may extend along the entire length or practically the versely thereof and serving for coating but a fraction and preferably a relatively small fraction of the surface area of the lead. It is preferred so to distribute the coated areas that at each part of the. length of the lead there are a plurality of spaced" coated regions. The raised imprint areas [6" of roller l'fi may bein any of a multiplicity of possible diverse patterns with .unraised spaces therebe'tween. The'co'rrespondin'g film areas on the lead may for instance be dots 24" shown illustratively diamond shaped and distributed in uncoated field 25" in 6,, or in a honeycomb pattern 2'4 affording discrete uncoated areas 25 that areframed. by film border. It is generally advantageous to form the coating, in longitudinal stripes, desirably along a steep helical thread and preferably a multiple, thread such as a triple or quadruple thread, as'shown in Fig. 2.. Of course, for this purpose. the raised imprint area It" on the roller !6 would be inclined at a very high pitch, as suggested in Fig. I, and. would be so spaced that the periphery of the lead I! as it is passed between printing roller l6 and the backing roller I8 will obtain the desired plurality of helical coatings at the desired pitch. In Figs. 2 and 3 a fragment of the lead thus coating is shown, with the high pitch helical coated at 24 and uncoated helical areas 25 intervening between the helical Coatings 24, said uncoated areas 25, as above suggested, occupying a lead surface area, considerably greater than. that occupied by the coating 24. Other patterns for distributing the film upon the lead surface with continuity of both the coated area and the uncoated area are obvious to those conversant with geometry. One example would be a sinusoidal line of adhesive of amplitude substantially the length of the lead.

The area coated'relative to that uncoated may be as large as desired, but in general the smaller that area the greater the ease of subsequent impregnation, and in practice a coated area of as little as 15 to 25 per cent of the superficial area of the lead, when applied in the manner stated,

is adequate for a truly effective bond of lead in its sheath, and: avoids any complication inthe impregnatingcycle or'the equipment: used? therefor.

The coating material. applied is in the form of any adhesive capable of drying to a film, which is incompatible with the grease impregnant and compatible with the carrier of the glue, usually water, that bonds the lead into its: sheath. of wood or the like.

There may be used for the purpose of forming the film on the lead, identically the same form of glue such as fish glue or glue made of polyvinyl emulsion, commonly applied to the groove of the wooden sheath for bonding'to the lead. However, any of various other adhesives, including those of the water emulsion type, of the water solution type; or of the chemical solvent type, will serve for the purpose.

As examples of the water emulsion type of-adhesive are polyvinyl acetate, polystyrene and latex of natural or synthetic rubber.

Examples of water solution type of adhesives are cellulose derivatives, such as carboxy methyl cellulose, polyvinyl alcohol, animal glues and casein.

Examples of chemical solvent type of adhesives useful for the purpose are cellulose nitrate, cellulose acetate, acrylic. esters, and phenol resins.

The water emulsion and water solution types of adhesives afford a mor tenacious bond for water soluble glue than do the chemical solvent type of film and are therefore ordinarily preferred.

In use of the water emulsion or water solution type of adhesive, it is desirable to include a small proportion, 15 to 50 per cent by weight, but generally not exceeding 30 per cent of a glue retardant, preferably a polyhydric alcohol, such as ethylene glycol, diethylene glycol, glycerol, pentaerithrytol, manitol or sorbitol. It is preferred, however, to use a polyhydric alcohol that is solid at room temperature such as sorbitol, in order to give increased solid content or body to the film. The polyhyclric alcohol acts to retard somewhat the filming of the adhesive and checks the gumming of the rollers of the'film coating equipment that might otherwise occur.

The adhesive thus supplied to the ungreased lead is allowed to dry and such drying may be expedited by a current of hot air blown thereover. In practice the amount of adhesive laid down on each coating area it of the printing roller I6 and transferred to the ungreased lead is so small that the film when dried upon the lead is almost immeasurably thin but may be detected bythe naked eye. The film in effect is sufficient to close only the surface ends of the pores of the lead and does not penetrate to any material extent into the core of the lead. Thin as the coated area is, it is yet substantially grease-impervious and effectively precludes the entry to or exit of grease with respect to said pores of the lead structure as are covered by the film.

Were the adhesive more liberally applied, it might readily pass bythe capillary action of the porous structure of the lead into the core thereof and to the extent that it thus enters, it would ex clude the grease impregnant and the dried adhesive in the pores would form hard writing spots in the lead. By resort totheextremely thin surface film set forth, assuranc is had that substantially the entire volume of the lead will be completely impregnated with the grease, without exclusion thereof from any region except that minor region occupied by the film at the outer surface, which region is cut away at the sharpened point of the pencil and so cannot afford any hard writing spots.

The lead is impregnated in conventional manner in an impregnating tank under vacuum with any grease commonly employed for impregnating leads to impart thereto the desired writing qualities. The grease does not penetrate the dry, substantially grease impervious filmed areas '24 previously put on the lead but freely enters through the relatively larger uncoated. surface areas of the lead and impregnates the various pores in that structure, as suggested in Fig. 4. Such grease spreads through the entire length of the lead, penetrating substantially the entire volume of the lead including that covered by, without however exuding through the substantially grease impervious film 24.

The lead is thereafter wiped by conventional wiping methods in which at most an extremely thin film of grease will remain upon the previously applied film 24, while exudation Of grease, especially in a warm room, may occur at the uncoated areas 25, all as suggested in Fig. 4.

The lead is now assembled in conventional manner between the two sections 26 and 2! of the wooden sheath. The lead accommodating groove of the wood sections is first coated as at "28 in conventional manner with the type of adhesive commonly introduced in such grooves, such as fish glue or a modified form of polyvinyl emulsion such as sold under the trade-mark Polybond and the faces of the sheath (not shown) are coated with hide glue or with synthetic glue of the polyvinyl emulsion type respectively, and the sections are pressed together with the lead'l'l in place therebetween. The adhesive used in the glue, while repelled by the grease exposed at the uncoated. areas 25 of the lead and ineffective for an adequate attachment at these areas, becomes anchored with thorough effectiveness at the coated areas 24. Any minor film of grease that covers such coated areas '24, as above stated, is ineffective to prevent the penetration of the'adhesive therethrough and does not interfere with the secure bond of such adhesive to the previously dried coated film 24 with which the glue is compatible by virtue of its water carrier.

The anchoring bond thus effected along the helical areas 24 Of the film coating above described, effectively distributes diagonally across the grain of the wood any pressure applied to the lead in writing, thereby lessening the chance of splitting of straight grained wood. Moreover the bond is especially secure, since by the arrangement set forth th entire length of the lead at each cross section thereof'is glue-bonded to the wood at three orfour distributed areas, as best shown in Fig. 3.

Thus there is no danger of a length of lead dropping out of the sheath in sharpening the pencil or in applying considerable pressure thereto in writing. Moreover the lead retains its original mechanical strength, unweakened by the erosion or pitting incurred in acid treatment thereof. Furthermore there is interposed no powder, crystals or other small particles between the lead and glue to serve as a barrier between the grease and the water soluble glue, and the pos sibility of slippage of the lead through such powder coating barrier, even though the barrier be securely bonded to the glue, is precluded.

Thus the lead is' adhesively bonded to the sheath directly and securely throughout its length, with the consequence that the base of the writing point (not pitted or otherwise weakened as for instance by acid treatment), is strong, especially as reinforced by the encompassing wooden sheath, so that the likelihood of point breakage under writing pressure is reduced.

The term grease as used in the specification and claims is intended to embrace not only grease as such, but oil and wax and mixtures of any two or all three of such materials in any manner commonly used or useful for impregnating lead to impart desired writing properties thereto.

The term pencil lead as used in the claims embraces within its scope not only black leads but leads of Various colors of the type which, like the black-leads are of porous construction, and adv -mit of treatment according to the present invenwidely difierent embodiments of this invention could be made without departing from th scope of the claims, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, what 'I claim as new and desire to secure by Letters Patent is:

1. As an article of manufacture, an unimpreghated pencil lead having grease impervious film coated areas compatible with the adhesive by which the lead is to bonded to its sheath, said 2. As a new article of manufacture, a pencil lead devoid of impregnant and having a substantially grease impervious but adhesive-compatible 'coating upon but a portion only of the surface of the lead, said coating being distributed lengthwise and peripherally of the lead surface, so that the lead may be impregnated with grease through those substantial exposed areas thereof that are devoid of such coating, said coated areas serving to afford a base for an effective adhesive patible with adhesive of the type employed for bonding lead into the sheath of a lead pencil.

QdQlLUsIiltB i. Ilhe combination recitedin claim 3-,,inwhich the film covers discrete areas of the lead sur-= face spaced apart by uncoated areas.

5. The combination recited in claim 3, in which the material. of the film is selected from grease impervious adhesive of the group consisting of polyvinyl acetate, polystyrene, latex of natural rubber and latex of synthetic rubber.

6. The combination recited in claim 3, in which the material of the film is selected fromv grease impervious adhesives of the group consisting of water emulsions and water solutions and having incorporated therewith a small proportion of retardant. selected from the polyhydric alcohols.

7. The combination recited in claim 6 in which the polyhydric alcohol is of type solid at room temperature.

8. As an article ofmanufacture, an ungreased pencil lead, having one or more spaced stripes generally longitudinally thereof upon its surface, said stripesbeing a coat incompatible with grease and compatible with the adhesive for bonding the lead into its sheath, stripes of uncoated lead surface intervening between said coated, stripes.

9. As an article of manufacture, an ungreased pencil lead having multiple helical stripes upon itsv surface, of coating incompatible with" grease and compatible with water soluble glue, said helical stripes affording intervening helical areas of uncoated lead surface.

10. As a new article of manufacture, a calcined lead having a thin, substantially grease imper vious but adhesive-compatlbe. film distributed lengthwise and peripherally of the ungreased lead surface and affording substantial areas of lead surface free of such film and distributed. lengthwise and peripherally of the lead, said lead being impregnated with grease. capable of exuding from the surface of the lead at said latter regions, said film substantially preventing exudation. of grease from the regions covered thereby, and affording a base for securev adhesive attachment of the lead in a sheath.

11. As an article of manufacture, a pencil lead having'grease impervious film coated areas compatible with the adhesive employed for bonding the lead into its sheath and. substantially closing the pores thereof substantially solely at the outer surface of the lead and devoid of such film at substantial areas of the lead surface intervening between the coated areas, and grease substantially impregnating the pores of the entire lead other than the exposed outer portions of those pores closed by grease impervious film.

12. As an article of manufacture, a pencil lead having directly upon its ungreased surface, spaced areas of film that are grease impervious and compatible with the adhesive employed for bonding the lead into its sheath, saidv film being distributed over the surface of the lead in a pattern that affords a plurality of spaced coated areas at each transverse cross section of the lead, the uncoated area of the leadbeing sub-- stantially greater than the coated area thereof.

13. As an article of manufacture, a pencil lead havingdirectly upon its ungreased surface, spaced generally longitudinal stripes of grease impervious film, said stripes being compatible with water soluble glue, the lead having stripe areas interventially precluding the passage of grease. therethrough.

14. The method of processinga calcined lead of the grease-impregnated type to assuresecurity of. adhesive bond; thereof within a: sheath, which method comprise applying upon the surface of the ungreased lead; a substantially greaseimpervious but adhesive film, said lead having at least the ends thereof unfilmecl to permit impregnation of the lead with grease.

1,5; The method of processing a calcined lead of the grease impregnated type to assure security of adhesive bond thereof within a sheath, which method comprises applying upon the surface of the ungreased lead a substantially grease impervious but adhesive film, said film covering materially less than the entire surface area of the lead and leaving uncoated surface areas of the lead that are. distributed both longitudinally and Deripherall-y thereof.

16. The method of, processing a calcined lead of the grease, impregnated type to assure security of water soluble glue bond thereof within a sheath, which process consists in imprinting upon the surface of the ungreased' lead a substantially rease impervious, but glue-compatible film, said film covering'materially less than the entire surface area of, the lead and leaving uncoated surface areas of the lead, that are distributed both longitudinally and peripherally thereof, and thereupon impregnating the lead with grease, whereby such grease will not exude through those areas of the lead that arefilm-coated.

17. In a lead pencil of the. type comprising a calcined. grease impregnated lead, an enclosing sheath therefor and adhesive interposed between the lead, and the. sheath, for bonding the lead within the sheath; the combination in which means is provided to assure an effective bond of the grease impregnated lead With respect to the sheath, said means; comprising grease impervious but adhesive-compatible film surface areas distributed lenthwise and peripherally of the lead and adheringdirectly to the surface of the lead structure with substantial intervals between the coated areas likewise distributed longitudinally and peripherally of" the lead and that are free of such film, the region of effective adhesive bond of the lead to the sheath being at said film covered areas,

18. In a lead pencil of the type comprising a calcined grease impregnated lead, enclosing sheath therefor, and adhesive interposed between the lead and the sheath for bonding the lead within the sheath; the combination in which means is provided to assure an effective bond of the grease impregnated lead with; respect to the sheath, said means comprising grease impervious, but adhesive-compatible film surface areas distributed lengthwise and peripherally of; the lead and ad-- hering directly to the surface of the lead structure with substantial interval between the filmed areas likewise, distributed longitudinally and peripherally of the lead and that are free of such film, each transverse.- cross section of the lead having a plurality of spaced filmed regions at each of which an effective adhesive bond exists of the lead with respect to the. sheath.

19. In a lead pencil of the type comprising a grease impregnated lead, a wooden sheath thereabout, and water soluble glue bonding the lead to the sheath; the combination in which the lead has helical areas thereof covered with film that is incompatible with grease and compatible with water-soluble glue, said film being substantially grease impervious. and being located substantially solely on the periphery of the lead, the wooden sheath being bonded to the lead at said film covered areas of the latter.

20. The method of manufacturing a lead pencil of the type comprising a grease impregnated lead, a sheath thereabout and a water soluble glue bond between the lead and the sheath, said method including the following steps in the following order: (a) coating upon the calcined but ungreased lead a thin surface covering of film of substantially grease impervious, glue-compatible substance; (b) impregnating with grease the lead thus coated; (c) removing excess grease from the surface of the lead; and (d) gluing the lead into its sheath, with resultant effective bond with the sheath at the surface covering of film on the lead.

21. The method of manufacturing a lead pencil of the type comprising a grease impregnated lead, a sheath thereabout and a water soluble glue bond between the lead and the sheath, said method including the following steps in the following order: (a) coating upon the calcined but ungreased lead a thin covering of film of substantially grease impervious, glue-compatible substance, said film covered areas of the lead being distributed over the length and periphery thereof and leaving exposed intervening uncoated lead areas likewise distributed longitudinally and peripherally of the 10 lead; (b) impregnating with grease the lead thus coated; (c) removing excess grease from the surface of the lead; and (d) gluing the lead into its sheath, with resultant effective bond of the lead surface with the sheath at the film coated areas of the lead.

22. The method as claimed in claim 21 of which the film coated areas are multiple helical stripes along and about the lead.

JOSEPH RAYMOND GRIECO.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,116,187 Chesler May 3, 1938 FOREIGN PATENTS Number Country Date 436 Great Britain of 1859 OTHER REFERENCES Pamphlet Atlas Sorbitol copyrighted 1947 by Atlas Powder Co. of Wilmington, Delaware.

Certificate of Correction Patent No. 2,515,118 July 11, 1950 JOSEPH RAYMOND GRIECO It is hereby certified that errorappears in the printed specification of the above numbered patent requirlng COIIGCtlOIl as follows:

fl Column 4, line 3, "for the ord coated read coatin 9,

f, X and thot the said Letters Patent should be read as corrected above, so that the same may conform to the record of the case in the Patent Ofrice. Signed and sealed this lOthfdaygof October, A. D. 1950.

THOMAS F. MURPHY,

Assistant Commissioner of Patents. 

